In order to increase comfort, pneumatic seats have been developed for use in vehicles, such as long haul trucks. Pneumatic seats have a pedestal that includes one or more air bags, a seat supported by the pedestal, and a control valve for controlling the volume of air within the air bags. Controlling the volume of air within the air bag(s) permits the occupant to adjust the height of the seat to suit the occupant's preference. By increasing the volume within the air bag(s), the air bag(s) inflates and raises the height of the seat. Decreasing the volume within the air bag(s) deflates the air bag(s) and lowers the height of the seat. Additionally, the pressure within the air bag(s) helps isolate the occupant from over the road vibration and bouncing when compared to non-pneumatic seats. Thus, the air bag(s) of a pneumatic seat functions not only as a shock absorber, but also as a seat height adjuster.
As noted above, air volume within the air bag(s) of a pneumatic seat may be adjusted by the control valve. Common control valves for pneumatic seats have a control paddle, an air bag inlet/outlet stem, an exhaust port, a slide member, and an air inlet stem. The air inlet stem is adapted to receive compressed air from an external source located elsewhere in the vehicle. The air bag inlet/outlet stem is in fluid communication with the air bag of the seat by an air hose. The air inlet stem may be selectively placed into fluid communication with the air bag inlet/outlet stem by an internal channel located within the slide member. The exhaust port selectively vents air from within the air bag inlet/outlet stem. The slide member is reciprocally mounted within the control valve, such that it may be reciprocated between a fill position, an exhaust position, and a closed position.
In the fill position, pressure is applied by the seat occupant to the control paddle of the control valve to slide the slide member within the control valve. As the slide member is slid within the control valve, the air inlet and air bag inlet/outlet stems are placed into fluid communication. Compressed air is permitted to flow through the control valve to supply air to the air bag, thereby inflating the air bag to the desired height. After the desired seat height is reached, the occupant releases the control valve to place the control valve back into its normal closed position, wherein airflow between the inlet and air bag inlet/outlet stems is blocked by the slide member. The seat height is maintained by the volume of air within the air bag until the occupant reactuates the control valve to lower the seat.
When the occupant desires to lower the seat, such as to its minimum level when leaving the cab of a truck, the occupant toggles the control paddle into the exhaust position to vent air from within the air bag. In most pneumatic control valves currently available, the occupant must apply a continuous pressure to the control paddle until the seat is at the desired height. In the exhaust position, the slide member is reciprocated within the control valve, such that the air bag inlet/out stem is placed into fluid communication with the exhaust port located within the control valve. The exhaust port vents the air to the atmosphere, thereby deflating the air bag and lowering the seat.
Prior attempts at automatically deflating the air bag of a pneumatic seat without requiring the occupant to continuously apply a pressure to the valve have resulted in moderately complex valves. One such valve utilizes a pin located on the exterior of the control valve that is used to lock the control paddle into the exhaust position. In such a valve, after the control paddle is displaced into the appropriate position, the pin is positioned to interfere with the control paddle and maintain it in the desired position. This often requires the occupant to use two hands to deflate the air bag; one hand to toggle the control paddle into the desired position and the other hand to lock the pin against the control paddle. Further, because such a valve requires the use of a pin to lock it into an automatic mode, this type of control valve tends to be larger then control valves without the pin. Therefore, although such control valves are effective at adjusting the height of pneumatic seats, they tend to be larger and more complicated to operate than desired.
Thus, there exists a need for a relatively simple and compact control valve for pneumatic seats that provides an automatic mode, wherein the valve is selectively held in an exhaust position to rapidly exhaust compressed air from the air bag of the seat. The present invention is directed to fulfilling this need.